Fig. 1.

T cells generate microvillus-originated particles upon TCR stimulation. a T cell microvillus polarization toward antigen-bearing B cells at the early stage of IS. SEM of resting single (left) or two adjacent (right) Jurkat T cells on PLL (i) and co-incubated with SEE-loaded Raji B cells (5, 30 min) (ii). Arrows indicate microvilli (red) and membrane ruffles (blue). b, c SEM of OTII naive CD4⁺ T cells on PLL with the anti-CD3 antibody (b) or OVA peptide/I-A^b and ICAM-1 (c) at various time points. Early (early stage, 1 min), mature (1–5 min), late (10–20 min), and terminal stages ( > 20 min). d Jurkat T cells were placed on anti-CD3-coated coverglass for 30 min and observed by TEM. The areas of TMPs and mitochondria were quantitated using ImageJ software. *P < 0.01 vs. mitochondria